Field of the Invention
The present invention generally relates to apparatus that control fluid flow. Particularly, the present invention relates to an improved component of a fluid flow control valve and to manufacturing the component.
Discussion of Prior Art
It is known that some fluid flow applications have valve assemblies to control fluid flow through the valve assemblies so as to minimize noise, vibration and cavitation. One such known valve assembly includes a tubular cage that fluid flows through. The cage has multiple flow channels through which the fluid flows and that are designed to control the velocity and pressure of the fluid through the cage and valve assembly.
The cage of the valve assembly is typically made from a series of stacked and relatively thin (about an average 0.125 inch thickness) cylindrical plates. The cage has numerous inlets and outlets formed along concentric circular peripheral surfaces of the plates. Flow channels are formed in the plates between the inlets and outlets by machining or cutting so flow is directed in the radial and circumferential directions within a given plate. The plates are stacked in a specific relative orientation and typically attached together by brazing.
Trying to manufacture a high quality known cage stack of plates in a reasonable lead time for a reasonable cost has been a challenge. There are inherent problems and disadvantages with manufacturing the known cage having a stack of plates.
For example, machining or stamping the plates can introduce unwanted debris that may attach to a plate or create edge surfaces that require deburring. Proper repeated stacking and aligning the separate plates can be difficult. It can also be a challenge to then hold the stacked and aligned plates during the brazing operation in order to achieve a good quality braze every time. One such alignment scheme is to provide extra material lobes with alignment holes which are machined off after brazing and, therefore, add manufacturing lead time and cost. This machining can also introduce unwanted contaminants the can enter flow channels, so care must be taken to block the flow channels or remove the contaminants.
Brazing itself also may present problems. Braze may be applied to the plates in various ways. To achieve an even and relatively thin layer of molten braze between adjacent plates, the plates must be flat. Any waviness of the plates will create areas where the braze will have difficulty flowing in an even and relatively thin manner to properly adhere adjacent plates together and, thereby, cause a lack of structural integrity. Plates can be ground flat but so doing increases manufacturing lead time, cost and the possible introduction of unwanted contaminants.
The known stacked plate-type cage manufacturing process generally requires that the cylindrical inside surface of the stack of brazed plates be machined to achieve the precision diameter and finish required to fit other components of the valve assembly. Machining the inside surface of the known cages can generate unwanted contaminants that can find their way into flow channels. It is very difficult to remove the contaminants and time consuming and costly to take measures to try to prevent ingress of the contaminants.
Thus, a need exist for an improved cage structure that does not suffer from the disadvantages and drawbacks of known plate-type of cages and the manufacturing processes used to produce them.